Surface Strengthening And Property Research Of Slider For Emulsion Pump

As a common equipment in coal mine machinery,emulsion pump is an energy conversion device which can convert mechanical energy into hydraulic energy.Its normal operation is a critical factor in safety operation of coal mine.The harsh working environment of coal mine and the long running time of emulsion pump can easily cause the wear failure of parts during working process.At present,there is serious wear failure phenomenon of slides in the emulsion pump station system of coal mine in Shenhua Group,which leads to the pressure drop of pump station,and seriously restricts the work efficiency of emulsion pump.Therefore,a new technology-ion source composite middle frequency magnetron sputtering technology is used to deposit high performance diamond like carbon(DLC)film to strengthen the slider surface,which is very meaningful to extend the service life of slide,significantly improves the working efficiency of emulsion pump,and meets the high reliability and long life requirements of pump station system under harsh conditions.It will also effectively promote the breakthrough at related technology fields,and achieve significant social and economic benefits.In this thesis,ion source composite middle frequency magnetron sputtering technology is used to deposite high performance DLC film on the substrate of slider.During the depositing process of DLC film,one technological parameter is independently changed including the flow rate of acetylene gas,substrate bias voltage and sputtering power of carbon target while other technological parameters are set as the same.The Raman,XPS,FTIR,AFM and SEM measurements are used to analyze the microtopography and microstructure of DLC film deposited by middle frequency magnetron sputtering technology under different process parameters.The mechanical properties and tribological properties of DLC film are tested and analyzed by nanoindentation instrument,scratch tester,UMT-3 friction and wear tester.Finally,an optimal test scheme is optimized to deposite DLC film to strengthen the surface of slider.This thesis provides a scientific theory basis and test basis for the development and application of new surface-enhanced technologies and processes.The influence of process parameters on the quality of DLC film deposited by middle frequency magnetron sputtering has been deeply studied in this thesis.The following conclusions are obtained:(1)The effect of acetylene flow rate.The surface roughness of DLC film deposited with the input of acetylene decreases firstly and then increases with the increase of acetylene flow rate.The roughness of DLC film deposited without the input of acetylene is low,but the stress is so high that the edge of film is exfoliated and the hardness is low.The result of Raman spectroscopy show that the ratio of sp3/sp2 firstly increases and then decreases with the increase of acetylene flow rate,and the hardness and elastic modulus also shows the same trend.The content of sp3 hybrid bond is the highest when the flow rate of acetylene is 60sccm.The film adhesion is 26N,which is 3times of the adhesion of film deposited without the input of acetylene.The average friction coefficient of films decreases with the increase of acetylene gas flow.The average friction coefficient reaches the minimum of 0.143 when the flow rate of acetylene is 60sccm,which is about 3 times lower than that of the substrate.(2)The effect of substrate bias voltage.The bias voltage of the substrate has a great effect on the hardness of DLC film.The hardness,elastic modulus and adhesion of the film reach the maximum(20.8GPa,170.8GPa and 25N)respectively at the bias voltage of 100V.At the same time,the sp3 hybrid bond also reaches the maximum,which proves that the sp3 hybrid bond content is an important factor in determining the mechanical properties of DLC film.The tribological property of the film firstly increases and then decreases with the increase of the bias voltage.The tribological property of the film not only relates to the self-hardness of the film,but also to the content of sp3 bonds inside the film due to the change of bias voltage and the surface state of film.(3)The effect of sputtering power.The results of Raman and XPS show that the ID/IG value decreases firstly and then increases with the increase of sputtering power.When the sputtering power is 8kW,ID/IG value reaches a minimum value at 8kW.Meanwhile,it can be seen that the G peak is broadened,which indicates an increase in bond disorder and an increase in the number of sp3 bonds in the film.The result of FTIR demonstrates that the content of bonding H in the film decreases with increase of sputtering power.At the same time,the friction coefficient of the film reaches the minimum when the sputtering power is 8kW.The high proportion of sp3/sp2 hybrid state,the high content of bonding H and the transfer film appeared on the friction surface of DLC film together make the DLC film have excellent tribological property.(4)The optimum DLC film process parameters are as follows:60sccm of the acetylene flow rate,100 V of substrate bias voltage,8kW of graphite target sputtering power.By observing the surface and cross-sectional morphology of the film,the film thickness is 2.4?m,and the film layer has a relatively uniform and dense internal structure.The results of Raman and XPS spectra show that the broadened G peak appears at near 1577 cm-1 and the weak peak D peak appears at near 1357 cm-1,which are the typical Raman peaks of DLC film.The sp3 hybrid bond relative content is about 36.4%calculated by Gaussian fitting.FTIR spectroscopy shows strong C-H stretching vibration at around 2925 cm-1,which indicates that the content of bonding H in the film is high,and the C atom in the film mainly exists in the form of sp3 bond.The mechanical and tribological properties of the film show that the hardness could reach 17GPa,which is much higher than that of substrate(5GPa).The friction coefficient is 0.143,which is three times lower than that of substrate(0.406).The wear volume also is much smaller than that of the substrate.And the film adhesion can reach 33N,which fully meets the requirements.The results demonstrate that the deposited DLC film shows excellent wear resistance and good mechanical properties,can strengthen the slider surface of emulsion pump,and meet the requirements of the slider.